Surface Energy‐Assisted Patterning of Vapor Deposited All‐Inorganic Perovskite Arrays for Wearable Optoelectronics

Abstract Solution‐based methods for fabricating all‐inorganic perovskite film arrays often suffer from limited control over nucleation and crystallization, resulting in poor homogeneity and coverage. To improve film quality, advanced vapor deposition techniques are employed for continuous film. Here, the vapor deposition strategy to the all‐inorganic perovskite films array, enabling area‐selective deposition of perovskite through substrate modulation is expanded. It can yield a high‐quality perovskite film array with different pixel shapes, various perovskite compositions, and a high resolution of 423 dpi. The resulting photodetector arrays exhibit remarkable optoelectronic performance with an on/off ratio of 13 887 and responsivity of 47.5 A W−1. The device also displays long‐term stability in a damp condition for up to 12 h. Moreover, a pulse monitoring sensor based on the perovskite films array demonstrates stable monitoring for pulse signals after being worn for 12 h and with a low illumination of 0.055 mW cm−2, highlighting the potential application in wearable optoelectronic devices.


Note S1: Calculation of surface free energy.
In Young's equation, the interfacial energy between solid and liquid ( sl  ) can be expressed by [1] : where θ is the contact angle, s  and l  is the surface free energy of solid and liquid, respectively.In addition, according to the Owens-Wendt-Rabel and Kaelble (OWRK) method, surface free energy (  ) can be assumed to consist of the dispersive component  can be expressed as the formula [2] : Combining the above two equations, we can obtain the equations:

( )
According to equation 3, the dependence of ).The solvents used in the calculation of surface free energy are displayed in Table S1 [3] .

Note S2: The process of the patterned substrate with different surface energies
The fabrication of the patterned substrate with different surface energies in the growth area as below: 1. Preparation of the patterned substrate: Firstly, the substrate was treated by the O2 plasma (PDC100B Plasma Cleaner) with 50 sccm O2 at 150 W for 180 s to get a hydrophilic surface.Secondly, the positive photoresist (S1813) was spun onto the substrate at 4000 rpm for 1 min and the patterned photoresist was obtained after exposure for 12 s and development (ZX238) for 30 s.And then SiO2 thin film was deposited on the substrate by magnetron sputtering (Kurt J. Lesker PVD75) at 200 W for 10 min.Subsequently, the substrate was placed into an octadecyl-trichlorosilane (OTS) solution (OTS: n-Hexane =1:200) for 15 min.Finally, after removing from the OTS solution, the substrate was immediately put into the acetone for ultrasonic cleaning for 10 min and cleaned with Deionized (DI) water to remove the photoresist and residual solvent.Table S2.The comparison of photoelectronic performance between the all-inorganic photodetector in this work and others reported previously.
Table S3.The comparison of photoelectronic performance between PPG sensors in this work and others reported previously.

(d
) and the polarity component ( p  ) and sl


are the dispersive and the polarity component of liquid.

2 .
Modulation of the surface energy in the growth area: Due to that the reaction between hydroxyl on the substrate and OTS is not instantaneous (FigureS4), premise modulation of surface energy can be achieved through controlling the self-assembly time of OTS treatment.The as-prepared substrate was immersed into the OTS solution with low concentration (OTS: n-Hexane =1:20000) for 1-40 min to obtain different surface energies.Due to the complete reaction in the non-growth area, the OTS only reacted with the hydroxyl group in the growth area, and low concentration OTS solution simultaneously alleviated the excessive reaction between OTS and the hydroxyl group.Finally, the substrate was cleaned with acetone and DI water immediately after removal from OTS.

Figure S1 .
Figure S1.Schematic illustration of the perovskite film deposition in the Tube furnace.The inset is a magnified schematic illustration of the placement position of perovskite powder and patterned substrate (black box) and temperature versus time curve of the tubular furnace (blue box).

Figure S2 .
Figure S2.Preparation of the patterned substrate.a) Schematic diagram about the preparation of the patterned substrate.b) Optical images of the substrate corresponding to (a).The scale bar is 200 μm.

Figure S3 .
Figure S3.The contact angle of H2O and DMF in the growth and non-growth areas, respectively.

Figure S4 . 6 Figure
Figure S4.Schematic illustration of the reaction between OTS and hydroxyl groups on the substrate surface.

Figure S6 .
Figure S6.SEM images of the patterned perovskite film with the surface energy growth area of 75.4,42.7, 34.7, 28.6, and 25.8 mJ/m 2 , respectively.The scale bar is 50 μm.

Figure
Figure S7.a) SEM images of the patterned perovskite film fabricated at 410 ℃ to 450 ℃.The scale bar is 50 μm.b) The dependence of coverage of the growth area (blue) and the non-growth area (red) on the growth temperature.

Figure S8 .
Figure S8.a) SEM images of the patterned perovskite film fabricated at 430 ℃ for 0, 15, 30, 45, and 60 min, respectively.The scale bar is 50 μm.b) The dependence of coverage of the growth area (blue) and the non-growth area (red) on the growth time.

Figure S9 .
Figure S9.SEM images of perovskite films prepared at 430 ℃ for a) 15 min and b) 30 min.The scale bar is 10 μm.c) The coverage of the growth area with growth time of 15 min and 30 min.

Figure S10 .
Figure S10.a) Magnified SEM images of the perovskite film on the growth area with the growth time of 0, 15, 30, 45, and 60 min, respectively.The scale bar is 10 μm.b-f)The width distribution of perovskite particles with the soaking time of 0, 15, 30, 45, and 60 min, respectively.g) The dependence of the perovskite particle width on the growth time.

Figure S11 .
Figure S11.a) The dependence of the thickness of perovskite film on the growth time.

Figure S15 .
Figure S15.a) CsPbX3 powder with different halogen ratios.b) SEM images of CsPbX3 film arrays.The scale bar is 200 μm.c) Partially magnified SEM images of CsPbX3 films.The scale bar is 5 μm.d) XRD, e) PL spectrum and absorption spectrum of the as-fabricated CsPbX3 with different halogen ratios.

Figure S16 .
Figure S16.(a) SEM cross-sectional view image of the perovskite film.(b) Schematic illustration of light reflection behavior on the specular and textured surface.

Figure
Figure S18.a) Schematic diagram of the perovskite PPG sensor structure.b) Photograph of the bending device.c) Circuit of the PPG sensor.

Figure S19 .
Figure S19.Current-time trace of the PPG sensor.

Figure S21 .
Figure S21.PPG signals measured after wearing for 12 h with and without daily life.